Spark plug



Aug. 18, 1964 M. R. ROSS 3,145,319

SPARK PLUG Filed Feb. 27. 1961 M? 0/ A. Fan

INVENTOR.

W 0. A/ w ATTOR/V' United States. Patent O 3,145,319 SPARK PLUG Minor R. Ross, 9222 Alwood, Houston, Tex. Filed Feb. 27, 1961, Ser. No. 91,866 2 Claims. (Cl. 313-125) Patented Aug. 18, 1964 "ice ternally threaded as 17 to receive the plug 18, the plug 18 having a screw driver receiving slot 19 in the upper end thereof to facilitate its installation and having the integral annular ring on the lower end face thereof which It is another object of the invention to provide a spark plug having novel means for reducing carbon accumulation on the electrodes.

It is a further object of the invention to provide a spark plug having novel means of sealing of the parts against leakage.

Another object of the invention is to provide a spark plug having means for reading the spark plug gap setting and for the adjustment of the spark gap without removing the plug from the motor head.

With the above and other objects in view, the invention has relation to certain novel features of construction, operation and arrangement of parts more particularly defined in the following specification and illustrated in the accompanying drawings, wherein:

FIGURE 1 is an elevational view, in cross section.

FIGURE 2 is a cross sectional end view taken on the line 22 of FIGURE 1.

Referring now more particularly to the drawings, the numeral 1 designates the body member having the reduced portion 2 which is externally threaded and on which the lower electrode, which is a fixed electrode, is mounted as at 3, and having the usual wrench receiving lugs 4, 4. The inside wall of the body member 1 has the enlarged chamber S, to receive the porcelain insulator 6, and the lower portion of the chamber 5 is reduced forming shoulder 7 and again reduced forming the shoulder 8, and the inside wall of the body member 1 is tapered inwardly, as 9, from the shoulder 8 through the reduced area 2.

The insulator 6 is formed to fit in the body member 1, and a double washer 11 is seated on the shoulders 7, 8 between the body member 1 and the insulator 6, the double washer being formed of suitable packing material by connecting a large and a small annular member so that the large member is joined at its inner periphery with the outer periphery of the inside member by an annular vertical connecting sleeve. sulator 6 conforms in shape to the inside wall of the body member 1, and extends outwardly from the chamber 5 at one end and from the body member 1 at the other end.

An axial bore 9 is formed in the insulator 6, which is enlarged forming the shoulder 10 and again enlarged forming the shoulder 12. An internally threaded portion 13 is mounted in the bore 9 and extends to and abuts the shoulder 10. The bushing 13 is enlarged at 14 to seat on the shoulder 10 and has an annular flange 15 which seats on the shoulder 12. The annulus between the bushing 13 and the insulator 6 is filled with a powdered cement 16 and the outside wall of the bushing 13 between the shoulder 10 and the annular flange 15 is coated with a suitable bonding cement before insertion into the bore 9. The upper end of the bore 9 is enlarged and in- The outside wall of the inextends into the area between the upper end of the bush ing 13 and the insulator 6, and presses downwardly on the powdered cement 16 to pack the cement firmly around the bushing 13.

An electrode 20, which is externally threaded, is mounted in the bushing 13 and extends axially through the insulator 6. The upper end of the electrode 20 is flanged at p 21, forming a wrench receiving nut, and has an integral connector 22 in which a screw driver slot 23 is formed. On the upper face of the flange 21, a guide mark 25 is formed, in alignment with the screw driver slot 23, and graduated markings as 24 are formed on the upper face of the porcelain insulator 6 to be read in conjunction with the mark 25 to determine the electrode spark gap. A portion of these markings may be colored, to indicate preferred settings, if desired.

The electrode 20 has its lower end face concaved as at 27 and the contact end of the electrode 3 has its upper face convex, as at 28, the rounded surfaces of these electrodes, being the areas subjected to the heat of combustion from the motor as well as the heat of the spark between them, tend to accumulate carbon deposits, however, by shaping them as described, such carbon will flake ofi and be exhausted through the motor, and the oil that may be deposited on the electrode 3 will readily run off of the rounded surface. The threads of the electrode 20 are treated with a heat resisting lubricant and powdered graphite to seal the threads against leakage and to assure ready movement of the electrode in the bushing for adjusting the spark gap.

When the plug is installed in a motor head, the spark gap between the electrodes 3, 20' may be determined by reading the gauge formed by the guide mark 25 and the graduated marks 24. When the electrodes become worn, as may be indicated by the use of a spark plug scope, the gap may be adjusted with a screw driver applied to the connector 22 and the rotation of the electrode 20. Similarly in fine tuning of a motor, the spark gap may be adjusted without removal of the plug, and uniform adjustments may be maintained by reference to the markings.

The internally threaded bushing 13, being firmly anchored in the bore 9, and sealed below the shoulder 8 by a bonding cement, and having the annular flange 15 seated on the shoulder 12, above which powdered cement is packed, provides a leak proof connection through the electrode 20 and the double shoulders formed in the lower portion ofthe chamber 5 on which are seated the double washer 11, against which the insulator bears, provides ample protection against leakage of combustion.

While the foregoing is considered a preferred form of the invention, it is by way of illustration only, the broad principle of the invention being defined by the appended claims.

What I claim is:

1. In a spark plug, a body member, a fixed electrode on said body member, an insulator mounted in and extending through said body member, an axial bore in said insulator, an. internally threaded bushing mounted in said bore, means for sealing said bushing in said bore at its lower end, and an enlarged area in said bore and powdered 3 cement packed in said enlarged area, a plug in the upper end of said enlarged area bearing against said powdered cement, and an externally threaded longitudinally adjustable electrode mounted in said bushing and extending through said insulator.

2. In a spark plug, a body member, a fixed electrode on said body member, an insulator mounted in and ex tending through said body member, an axial bore in said insulator, an internally threaded bushing mounted in said bore, means for sealing said bushing in said bore at its lower end, and an enlarged area in said bore and powdered cement packed in said enlarged area, a plug in the upper end of said enlarged area bearing against said powdered cement, and an externally threaded longitudinally adjustable electrode mounted in said bushing and extending through said insulator and means on the upper end of 4: said insulator and said adjustable electrode for determining the spark gap between the adjacent ends of the said fixed and adjustable electrodes.

References Cited in the file of this patent UNITED STATES PATENTS 698,042 Mosler Apr. 22, 1902 771,683 Svenson Oct. 4, 1904 1,267,597 Schultz May 28, 1918 1,401,585 Collins Dec. 27, 1921 1,930,003 Erny Oct. 10, 1933 2,238,396 Rabezzana et a1 Apr. 15, 1941 2,616,406 Thomas Nov. 4, 1952 FOREIGN PATENTS 7,789 Great Britain Jan. 4, 1912 

1. IN A SPARK PLUG, A BODY MEMBER, A FIXED ELECTRODE ON SAID BODY MEMBER, AN INSULATOR MOUNTED IN AND EXTENDING THROUGH SAID BODY MEMBER, AN AXIAL BORE IN SAID INSULATOR, AN INTERNALLY THREADED BUSHING MOUNTED IN SAID BORE, MEANS FOR SEALING SAID BUSHING IN SAID BORE AT ITS LOWER END, AND AN ENLARGED AREA IN SAID BORE AND POWDERED CEMENT PACKED IN SAID ENLARGED AREA, A PLUG IN THE UPPER END OF SAID ENLARGED AREA BEARING AGAINST SAID POWDERED CEMENT, AND AN EXTERNALLY THREADED LONGITUDINALLY ADJUSTABLE ELECTRODE MOUNTED IN SAID BUSHING AND EXTENDING THROUGH SAID INSULATOR. 